Photomask and method of repairing photomask

ABSTRACT

The present disclosure provides a photomask and a method for repairing a photomask. The photomask includes a substrate, a reflective multi-layer stack over the substrate, a capping layer over the reflective multi-layer stack, an absorber layer over the capping layer, a first patch layer in direct contact with the absorber layer, and a second patch layer over a surface of the first patch layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/586,393, filed Sep. 27, 2019, and claims the benefit thereof under 35U.S.C. 120.

BACKGROUND

In the semiconductor industry, there is a trend toward higher devicedensity. In order to achieve such higher density, smaller features arerequired. Such requirements frequently involve scaling down devicegeometries to achieve lower fabrication costs, higher device integrationdensity, higher speeds, and better performance. Along with theadvantages from geometry size reductions, improvements to semiconductordevices are being made.

As semiconductor industry continues to evolve, advanced photolithographytechniques have been widely used in integrated circuit fabricationoperation. Photolithography operations may include techniques pertinentto coating a photoresist layer on a wafer and exposing the wafer to anexposing source.

Masks can be used in semiconductor fabrication operations to transfer apredetermined pattern onto a substrate. For example, after forming aphotoresist layer over a substrate, the photoresist layer can be exposedto an actinic radiation through a mask. For another example, afterforming a photoresist layer over a substrate, the photoresist layer canbe exposed to an actinic radiation reflected by a mask. Thereby, aphotoresist pattern can be formed by subsequent development.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A is a schematic drawing illustrating a top view of a photomask,according to some embodiments of the present disclosure.

FIG. 1B is a schematic drawing illustrating a cross sectional view takenalong line A-A′ of FIG. 1A, showing a cross-sectional view of aphotomask, according to some embodiments of the present disclosure.

FIG. 1C is a schematic drawing illustrating a cross sectional view takenalong line B-B′ of FIG. 1A, showing a cross-sectional view of aphotomask, according to some embodiments of the present disclosure.

FIG. 2A is a schematic drawing illustrating an enlarged cross sectionalview of a pattern region of a photomask, according to some embodimentsof the present disclosure.

FIG. 2B is a schematic drawing illustrating a top view of a patternregion of a photomask, according to some embodiments of the presentdisclosure.

FIG. 2C is a schematic drawing illustrating an enlarged cross sectionalview of an isolation region of a photomask, according to someembodiments of the present disclosure.

FIG. 2D is a schematic drawing illustrating a top view of an isolationregion of a photomask, according to some embodiments of the presentdisclosure.

FIG. 3A is a schematic drawing illustrating a cross sectional view of aphotomask, according to some embodiments of the present disclosure.

FIG. 3B is a schematic drawing illustrating a top view of a photomask,according to some embodiments of the present disclosure.

FIG. 4A is a schematic drawing illustrating an enlarged cross sectionalview of a pattern region of a photomask, according to some embodimentsof the present disclosure.

FIG. 4B is a schematic drawing illustrating a top view of a patternregion of a photomask, according to some embodiments of the presentdisclosure.

FIG. 4C is a schematic drawing illustrating an enlarged cross sectionalview of an isolation region of a photomask, according to someembodiments of the present disclosure.

FIG. 4D is a schematic drawing illustrating a top view of an isolationregion of a photomask, according to some embodiments of the presentdisclosure.

FIG. 5A shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5B shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5C shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5D shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5E shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5F shows a flow chart representing a method for repairing aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 5G shows a flow chart representing a method for cleaning aphotomask, in accordance with some embodiments of the presentdisclosure.

FIG. 6 is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 7A to 7D are cross sectionals view of a photomask duringintermediate repairing operations, according to some embodiments ofpresent disclosure.

FIG. 7A′ to FIG. 7B′ are cross sectional views of a photomask duringintermediate repairing operations, according to some embodiments ofpresent disclosure.

FIG. 8 is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 9A to 9C are cross sectional views of a photomask duringintermediate repairing operations, according to some embodiments ofpresent disclosure.

FIG. 9A′ is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 10A to IOF are cross sectional views of a photomask duringintermediate manufacturing operations, according to some embodiments ofpresent disclosure.

FIG. 11 to 14 show cross sectionals view of a photomask duringintermediate cleaning operations, according to some embodiments ofpresent disclosure.

FIG. 15A is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 15B is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 15C is a cross sectional view of a photomask during intermediaterepairing operations, according to some embodiments of presentdisclosure.

FIG. 16A shows a relationship between a thickness of deposited patchlayer in pattern region and number of cycles of cleaning operationperformed, as well as a relationship between a change of criticaldimension in pattern region and number of cycles of cleaning operationperformed, according to some embodiments of present disclosure.

FIG. 16B shows a relationship between a thickness of deposited patchlayer in isolation region and number of cycles of cleaning operationperformed, according to some embodiments of present disclosure.

FIG. 16C shows a relationship between a thickness of deposited patchlayer and number of cycles of cleaning operation performed, according tosome embodiments of present disclosure.

FIG. 17 shows a flow chart representing a method for fabricating asemiconductor device, in accordance with some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the terms“substantially,” “approximately,” or “about” generally means within avalue or range which can be contemplated by people having ordinary skillin the art. Alternatively, the terms “substantially,” “approximately,”or “about” means within an acceptable standard error of the mean whenconsidered by one of ordinary skill in the art. People having ordinaryskill in the art can understand that the acceptable standard error mayvary according to different technologies. Other than in theoperating/working examples, or unless otherwise expressly specified, allof the numerical ranges, amounts, values and percentages such as thosefor quantities of materials, durations of times, temperatures, operatingconditions, ratios of amounts, and the likes thereof disclosed hereinshould be understood as modified in all instances by the terms“substantially,” “approximately,” or “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thepresent disclosure and attached claims are approximations that can varyas desired. At the very least, each numerical parameter should at leastbe construed in light of the number of reported significant digits andby applying ordinary rounding techniques. Ranges can be expressed hereinas from one endpoint to another endpoint or between two endpoints. Allranges disclosed herein are inclusive of the endpoints, unless specifiedotherwise.

During the fabrication or using of photomask, defects may be introducedon a surface of the photomask. For one example, particles may fall onthe photomask. For another example, when fabricating an extremeultraviolet (EUV) mask, carbon contamination may occur due to permeationof oxygen and/or hydrogen during fabrication. The aforesaid defects maycause degradation of photolithography performance.

In order to remove such defects and/or particles and extend the lifetimeof photomask, cleaning operation may be performed on the photomask. Inorder to effectively remove particles, the cleaning operation mayinclude applying reactive wet chemicals (which may include basicformulation, acidic formulation, and/or hydrogen dioxide) and/orperforming photoresist strip. It is observed that the photomask maysuffer from defect such as (but not limited to) an absence of a desiredphotomask feature, a damaged or absent scattering bar, an absence ofmaterial from a larger pattern feature, or any undesirable material lossof the photomask, the photomask may be subjected to be repaired tocompensate such defects. Specifically, such defects can be observedafter fabrication or using of the photomask. However, the repaired partof the repaired photomask may again suffer from material loss (orpeeling) after cycle(s) of cleaning operations, thence the shape of themask pattern as a whole after cleaning may deviate from thepredetermined design layout, and the pattern form on an underlyingphotoresist layer may deviate from the predetermined pattern. It mayalso be observed that a critical dimension of a feature may beundesirably changed after cleaning.

In order to alleviate material loss under cleaning operation, and toreduce the impact of contaminants/particles on the photomask, thepresent disclosure provides a photomask and a method for repairing thephotomask. Specifically, the present disclosure provides a method ofrepairing a photomask suffered from various defects, and alleviating thematerial loss of the repaired patch during cleaning operation. Therepairing operation in the present disclosure can be performed aftermanufacturing a photomask and before performing a lithography operationusing the photomask, or, after performing cycle(s) of lithographyoperation(s) using the photomask.

Referring to FIG. 1A, FIG. 1B and FIG. 1C, FIG. 1A is a schematicdrawing illustrating a top view of a photomask, FIG. 1B is a schematicdrawing illustrating a cross sectional view taken along line A-A′ ofFIG. 1A, showing a cross-sectional view of a photomask, FIG. 1C is aschematic drawing illustrating a cross sectional view taken along lineB-B′ of FIG. 1A, showing a cross-sectional view of a photomask,according to some embodiments of the present disclosure. A photomask 100is a patterned reflective mask, such as an EUV mask. The photomask 100includes a substrate 1, which may be a low thermal expansion materialsubstrate. The photomask 100 may further include a reflective multilayerstack 2 above the substrate 1, and a capping layer 3 above thereflective multilayer stack 2. The reflective multilayer stack 2 mayinclude a plurality of alternative material layers (e.g.Molybdenum-Silicon (Mo—Si) stacks). In some embodiments, the cappinglayer 3 may include ruthenium oxide (RuO₂), ruthenium compound, or othersuitable materials. A buffer layer (not shown in FIG. 1A to FIG. 1C) canoptionally be disposed above the capping layer 3.

Furthermore, the photomask 100 includes a pattern region 6 above thecapping layer 3 and a border region 7 at a peripheral area of thepattern region 6, wherein an absorber layer 4 (shown in FIG. 2A) isdisposed in the pattern region 6. In some embodiments, the pattern ofthe absorber layer 4 in the pattern region 6 may include materials suchas tantalum boron oxide-based materials (such as tantalum borate, TaBO),tantalum boron nitride (TaBN), or other suitable materials for absorbingEUV radiation. Alternatively, the absorber layer 4 can also be made ofsilicon derivatives, such is silicon oxide (SiO₂) or silicon carbide(SiC). In some embodiments, some resolution enhancement features, suchas scattering bars, can be disposed in the pattern region 6. In someembodiments, a black border region 7′ (which may be a trench forexposing a top surface of the substrate 1 in some embodiments) may atleast partially surround the pattern region 6 and spacing between theborder region 7 and the pattern region 6. A discharge bridge region 7 zmay be disposed to be across the black border region 7′ and provide aninterconnect structure between the border region 7 and the patternregion 6.

Referring to FIG. 2A and FIG. 2B, FIG. 2A is a schematic drawingillustrating an enlarged cross sectional view of a pattern region of aphotomask, FIG. 2B is a schematic drawing illustrating a top view of apattern region of a photomask, according to some embodiments of thepresent disclosure. An absorber layer 4 is disposed above the cappinglayer 3 (which is the front side FS of the photomask 100) and in thepattern region 6 of the photomask 100. The pattern of the absorber layer4 can be transferred to a photoresist layer by a reflectivephotolithography operation. In some embodiments, a first patch layer 12is disposed over the front side FS of the photomask 100. A bottomsurface of the first patch layer 12 may be coplanar with a bottomsurface of the absorber layer 4. In some embodiments, the first patchlayer 12 is adjacent to a sidewall of the absorber layer 4. The firstpatch layer 12 may be in direct contact with the sidewall of theabsorber layer 4 and the front side FS of the photomask 100. The firstpatch layer 12 be composed of a material that has a relatively higherabsorb rate of EUV, such as chromium-containing material. A second patchlayer 18 can further be formed above the first patch layer 12. The firstpatch layer 12 may be entirely covered by the second patch layer 18. Thesecond patch layer 18 may further cover a sidewall of the first patchlayer 12. In some embodiments, the second patch layer 18 covers theentire surface of the first patch layer 12 exposed from the absorberlayer 4. Optionally, a bottom surface of the second patch layer 18 maybe in contact with the front side FS of the photomask 100. A material ofthe first patch layer 12 is different from a material of the secondpatch layer 18. The material of the second patch layer 18 may have alower etch rate than the material of the first patch layer 12 under atleast one of the following types of chemicals or treatment: acidicformulation, basic formulation, hydrogen dioxide (H₂O₂), Sulfuric acid(H₂SO₄), Ammonium hydroxide (NH₄OH), combination of deionized water andozone (O₃), application of deionized water and irradiation of light(such as ultraviolet (UV)), combination of H₂O and hydrogen dioxide, SClsolution (solution including NH₄OH, H₂O₂, H₂O), SPM solution (solutionincluding H₂SO₄, H₂O₂, H₂O), reactive chemical, or any other chemicalsuitable for cleaning a photomask. In some embodiments, a material ofthe second patch layer 18 may be a silicon derivative material, forexample, silicon oxide (SiO₂), silicon carbide (SiC), or the like.

Furthermore, a thickness T12 of the first patch layer 12 is comparableto a thickness T4 of the absorber layer 4. For example, a thickness T12of the first patch layer 12 may be in a range from about 60 nm to about90 nm when a thickness T4 is around 70 nm, but the present disclosure isnot limited thereto. For another example, a thickness T12 is in a rangefrom about 90% of thickness T4 to about 110% of thickness T4, but thepresent disclosure is not limited thereto. A thickness T18T of thesecond patch layer 18 above the first patch layer 2 is thicker than athickness T18S of the second patch layer 18 adjacent to a sidewall ofthe first patch layer 12. In some embodiments, the thickness T18T is ina range from about 1 nm to about 10 nm, and the thickness T18S is in arange from about 0.5 nm to about 10 nm. If thickness T18T is thinnerthan 1 nm or the thickness T18S is thinner than 0.5 nm, the second patchlayer 18 may not effectively protect the first patch layer 2 from beingremoved under the aforesaid cleaning chemical or cleaning treatment forcleaning operation. If thickness T18T is thicker than 10 nm or thethickness T18S is thicker than 10 nm, shadowing effect may be induced inexposure operation.

Referring to FIG. 2C and FIG. 2D, FIG. 2C is a schematic drawingillustrating an enlarged cross sectional view of an isolation region ofa photomask, FIG. 2D is a schematic drawing illustrating a top view ofan isolation region of a photomask, according to some embodiments of thepresent disclosure. Particles PA may fall on to an isolation region ISOof the photomask 100, and an incident radiation (such as EUV) may bereflected by the particles PA, thereby inducing undesirable defects on aphotoresist layer when transferring the mask pattern in lithographyoperation. In some embodiments, the isolation region ISO may be in theblack border region 7′ as illustrated in FIG. 1A to FIG. 1C. In order toalleviate reflection of EUV in the isolation region ISO (in some cases,in the black border region 7′) during exposure operation, a first patchlayer 12 can be disposed above the particles PA in the isolation regionISO, and a second patch layer 18 can be disposed above the first patchlayer 18. An area of the second patch layer 18 is greater than an areaof the first patch layer 12 from a top perspective view, as shown inFIG. 2C. In some of the embodiments, an area of the second patch layer18 is less than an area of the isolation region ISO from a topperspective view, thereby a portion of the substrate 1 is exposed fromthe second patch layer 18 in the isolation region ISO. In someembodiments, if the particles PA locate at several separated locations,a plurality of separated first patch layer 12 and the second patch layer18 can be formed at separated locations accordingly.

The material of the first patch layer 12 and the material of the secondpatch layer 18, as discussed in FIG. 2A to FIG. 2B, may be able toeffectively absorb a substantial portion of incident radiationirradiated thereon. Alternatively stated, in the case of the photomaskis an EUV mask, at least one of the first patch layer 12 and thematerial of the second patch layer 18 can be selected from materialscapable of absorbing EUV (e.g., λ=13.5 nm). For example, a material ofthe first patch layer 12 can be chromium-containing material, and thesecond patch layer 18 can be a silicon derivative material, such assilicon oxides or silicon carbides.

Referring to FIG. 3A and FIG. 3B, FIG. 3A is a schematic drawingillustrating a cross sectional view of a photomask, FIG. 3B is aschematic drawing illustrating a top view of a photomask (withoutshowing the pellicle layer), according to some embodiments of thepresent disclosure. A photomask 100 x at least include a substrate 1 x,an absorber layer 4, and a pellicle layer 1 y. The photomask 100 x is anoptical mask that allows light (such as 193 nm illumination) to passthrough the substrate 1 x and the pellicle layer 1 y, wherein a portionof light is absorbed by the absorber layer 4. Optionally, a shieldinglayer 1 s is further disposed on the absorber layer 4 and under thepellicle layer 1 y.

Similar to the discussion in FIG. 2A to FIG. 2B, the first patch layer12 is disposed over the first side 1 x′ of the substrate 1 x. A bottomsurface of the first patch layer 12 may be coplanar with a bottomsurface of the absorber layer 4. In some embodiments, the first patchlayer 12 is adjacent to a sidewall of the absorber layer 4. The firstpatch layer 12 may be in direct contact with the sidewall of theabsorber layer 4 and the first side 1 x′ of the substrate 1 x. A secondpatch layer 18 can further be formed above the first patch layer 12. Thefirst patch layer 12 may be entirely covered by the second patch layer18. The second patch layer 18 may further cover a sidewall of the firstpatch layer 12. In some embodiments, the second patch layer 18 coversthe entire surface of the first patch layer 12 exposed from the absorberlayer 4. Optionally, a bottom surface of the second patch layer 18 maybe in contact with the first side 1 x′ of the photomask 100. The firstpatch layer 12 contains a material that is capable of absorbing opticallight (e.g. 193 nm wavelength light), such as chromium-containingmaterial. A material of the first patch layer 12 is different from amaterial of the second patch layer 18. The material of the second patchlayer 18 may have a lower etch rate than the material of the first patchlayer 12 under at least one of the following types of chemicals ortreatment: acidic formulation, basic formulation, hydrogen dioxide(H₂O₂), Sulfuric acid (H₂SO₄), Ammonium hydroxide (NH₄OH), combinationof deionized water and ozone (O₃), application of deionized water andirradiation of light (such as ultraviolet (UV)), combination of H₂O andhydrogen dioxide, SCl solution (solution including NH₄OH, H₂O₂, H₂O),SPM solution (solution including H₂SO₄, H₂O₂, H₂O), reactive chemical,or any other chemical suitable for cleaning a photomask. In someembodiments, a material of the second patch layer 18 may be a siliconderivative material, for example, silicon oxide (SiO₂), silicon carbide(SiC), or the like. The criticality of thickness of the first patchlayer 12 and the second patch layer 18 may be similar to the counterpartin FIG. 2A to FIG. 2B.

Referring to FIG. 4A and FIG. 4B, FIG. 4A is a schematic drawingillustrating a cross sectional view of a pattern region of a photomask,FIG. 4B is a schematic drawing illustrating a top view of a patternregion of a photomask, according to some embodiments of the presentdisclosure. A photomask 100 y is similar to the photomask 100 asdiscussed in FIG. 1A to FIG. 2D, which at least includes a substrate 1(which may be a low thermal expansion material substrate), a reflectivemultilayer stack 2 above the substrate 1, a capping layer 3 above thereflective multilayer stack 2, and an absorber layer 4 above the cappinglayer 3. Except herein the second patch layer 18 is disposed over thefront side FS of the photomask 100 y, and the second patch layer 18 isadjacent to a sidewall of the absorber layer 4. The material of thesecond patch layer 18 may have a high absorb rate of EUV radiation, suchas a silicon derivative material, for example, silicon oxide (SiO₂),silicon carbide (SiC), or the like. In some embodiments, a bottomsurface of the second patch layer 18 may be coplanar with a bottomsurface of the absorber layer 4. In some embodiments, a top surface ofthe second patch layer 18 may be exposed from the absorber layer 4. Thesecond patch layer 18 may be in direct contact with the sidewall of theabsorber layer 4 and/or the front side FS of the photomask 100 y.Furthermore, a thickness T18′ of the second patch layer 18 is comparableto a thickness T4 of the absorber layer 4. For example, a thickness T18′of the first patch layer 12 may be in a range from about 60 nm to about90 nm when the thickness T4 is about 70 nm, but the present disclosureis not limited thereto. For another example, a thickness T18′ is in arange from about 90% of thickness T4 to about 110% of thickness T4, butthe present disclosure is not limited thereto. It should be noted thatin the case of a material of the second patch layer 18 is capable ofabsorbing light having other wavelength, such as 193 nm light, theaforesaid structure in FIG. 4A to FIG. 4B can also be applied to thephotomask 100 x as discussed in FIG. 3A.

Referring to FIG. 4C and FIG. 4D, FIG. 4C is a schematic drawingillustrating a cross sectional view of an isolation region of aphotomask, FIG. 4D is a schematic drawing illustrating a top view of anisolation region of a photomask, according to some embodiments of thepresent disclosure. Particles PA may fall on to an isolation region ISOof the photomask 100 y, and an incident radiation (such as EUV) may bereflected or deflected by the particles PA, and induce defects om aphotoresist layer in lithography operation. Similar to the discussion inFIG. 2C to FIG. 2D, the isolation region ISO may be in the black borderregion 7′ as illustrated in FIG. 1A to FIG. 1C. In order to alleviatereflection of EUV in the isolation region ISO (in some cases, in theblack border region 7′) during exposure operation, a second patch layer18 can be disposed above the particles PA fell on the isolation regionISO. In some of the embodiments, an area of the second patch layer 18 isless than an area of the isolation region ISO from a top perspectiveview, thereby a portion of the substrate 1 is exposed from the secondpatch layer 18 in the isolation region ISO. In some embodiments, if theparticles PA locate at several separated locations, a plurality ofseparated second patch layer 18 can be formed at separated locationsaccordingly. As previously discussed in FIG. 3A to FIG. 3B, a materialof the second patch layer 18 can be a silicon derivative material, suchas silicon oxide (SiO₂), silicon carbide (SiC), or other material thatis capable of absorbing EUV.

Referring to FIG. 5A, FIG. 5A shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 1000 for repairing a photomask includesproviding a photomask (operation 1001, which can be referred to FIG. 6or FIG. 10D), applying a first gas over the photomask (operation 1003,which can be referred to FIG. 7A or FIG. 10E), depositing a first patchlayer adjacent to the absorber layer (operation 1006, which can bereferred to FIG. 7A to FIG. 7B, or FIG. 10E), applying a second gas overthe photomask (operation 1009, which can be referred to FIG. 7C or FIG.10F), and depositing a second patch layer over the first patch layer(operation 1011, which can be referred to FIG. 7C to FIG. 7D, or FIG.10F).

Referring to FIG. 5B, FIG. 5B shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 1100 for fabricating a photomask includesproviding a photomask (operation 1101, which can be referred to FIG. 6or FIG. 10D), determining a first area of the photomask to be repaired(operation 1103, which can be referred to FIG. 6) or FIG. 10D, applyinga chromium-containing gas over the photomask (operation 1106, which canbe referred to FIG. 7A or FIG. 10E), depositing a first patch layeradjacent to the absorber layer (operation 1109, which can be referred toFIG. 7A to FIG. 7B, or FIG. 10E), applying a silicon-containing gas overthe photomask (operation 1111, which can be referred to FIG. 7C or FIG.10F), depositing a second patch layer over the first patch layer(operation 1113, which can be referred to FIG. 7C to FIG. 7D, or FIG.10F), inspecting the photomask (operation 1115, which can be referred toFIG. 7D or FIG. 10F), performing cleaning operation on the photomask(operation 1117, which can be referred to FIG. 11 to FIG. 14), andinspecting the photomask (operation 1119, which can be referred to FIG.15A, FIG. 15B or FIG. 15C).

Referring to FIG. 5C, FIG. 5C shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 1200 for fabricating a photomask includesproviding a photomask (operation 1201, which can be referred to FIG. 8),determining a second area of an isolation region of the photomask(operation 1203, which can be referred to FIG. 8), depositing a firstpatch layer in the second area (operation 1206, which can be referred toFIG. 9A to FIG. 9B), depositing a second patch layer over the firstpatch layer (operation 1209, which can be referred to FIG. 9C), andperforming cleaning operation on the photomask (operation 1211, whichcan be referred to FIG. 11 to FIG. 14).

Referring to FIG. 5D, FIG. 5D shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 2000 for fabricating a photomask includesproviding a photomask (operation 2004, which can be referred to FIG. 6),applying a silicon-containing gas over the photomask (operation 2007,which can be referred to FIG. 7A′), and depositing a first siliconderivative layer adjacent to the absorber layer (operation 2013, whichcan be referred to FIG. 7A′ to FIG. 7B′).

Referring to FIG. 5E, FIG. 5E shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 2100 for fabricating a photomask includesproviding a photomask (operation 2101, which can be referred to FIG. 6),determining a first area of the photomask to be repaired (operation2103, which can be referred to FIG. 6), applying a silicon-containinggas over the photomask (operation 2105, which can be referred to FIG.7A′), depositing a first silicon derivative layer adjacent to theabsorber layer (operation 2107, which can be referred to FIG. 7A′ toFIG. 7B′), inspecting the photomask (operation 2109, which can bereferred to FIG. 7B′), performing cleaning operation on the photomask(operation 2111, which can be referred to FIG. 11 to FIG. 14), andinspecting the photomask (operation 2209, which can be referred to FIG.15A, FIG. 15B or FIG. 15C).

Referring to FIG. 5F, FIG. 5F shows a flow chart representing a methodfor repairing a photomask, in accordance with some embodiments of thepresent disclosure. The method 2200 for fabricating a photomask includesproviding a photomask (operation 2203, which can be referred to FIG. 8),determining a second area of an isolation region of the photomask(operation 2205, which can be referred to FIG. 8), depositing a secondsilicon derivative layer in the second area (operation 2207, which canbe referred to FIG. 9A′), and performing cleaning operation on thephotomask (operation 2209, which can be referred to FIG. 11 to FIG. 14).

Referring to FIG. 5G, FIG. 5G shows a flow chart representing a methodfor cleaning a photomask, in accordance with some embodiments of thepresent disclosure. The method 7000 for cleaning a photomask includesperforming cleaning operation on a photomask (operation 7999). Theoperation 7999 includes applying a cleaning chemical on the photomask(sub-operation 7001, which can be referred to FIG. 11), applyingphotoresist on the photomask (sub-operation 7003, which can be referredto FIG. 12), and applying a cleaning chemical on the photomask(sub-operation 7005, which can be referred to FIG. 13).

FIG. 6 and FIG. 7A to FIG. 7D provide a method for repairing a patternregion 6 of the photomask 100; FIG. 6 and FIG. 7A′ to FIG. 7B′ provideanother method for repairing a pattern region 6 of the photomask 100 y.FIG. 8 and FIG. 9A to FIG. 9C provide a method for repairing anisolation region ISO of the photomask 100 or photomask 100 y; FIG. 8 andFIG. 9A′ provide another method for repairing an isolation region ISO ofthe photomask 100 y or photomask 100. FIG. 10A to FIG. 10F provideanother method for repairing a photomask 100 x. The repairing operationin the present disclosure can be performed after manufacturing aphotomask and before performing a lithography operation using thephotomask, or, after performing cycle(s) of lithography operation(s)using the photomask.

Referring to FIG. 6, FIG. 6 is a cross sectional view of a photomaskduring intermediate repairing operations, according to some embodimentsof present disclosure. A photomask 100 as discussed in FIG. 1A to FIG.2D is provided. In order to obtain a pattern of the absorber layer 4 ofa fabricated photomask 100 similar to a predetermined pattern, aninspection operation is performed on the photomask 100. The defect mayinclude, but not limited to, an absence of a desired photomask feature,a damaged or absent scattering bar, an absence of material from a largerpattern feature, or any undesirable material loss of the photomask. Forexample, the pattern of the fabricated photomask 100 may be compared toa predetermined layout design, thereby identify the defect of fabricatedphotomask 100 that is different from the original desirable design. Foranother example, the defect of the fabricated photomask 100 may also beidentified by experience or by algorithm. As shown in FIG. 6, a firstpredetermined area DA1 having a defect is identified.

Referring to FIG. 7A and FIG. 7B, FIG. 7A is a cross sectional view of aphotomask during intermediate repairing operations, FIG. 7B is a crosssectional view of a photomask during intermediate repairing operations,according to some embodiments of present disclosure. In order to repairor mitigate the defect, after inspecting the defect thereon, thefabricated photomask 100 is positioned in a repair chamber 309. A firstgas 312 is introduced into the repair chamber 309 and applied on thephotomask 100. The first gas 312 is a precursor for forming a firstpatch layer 12. The first gas 312 may be a metal-containing gas, such asa chromium-containing gas which can serve as a precursor for forming achromium-containing layer. For example, the first gas 312 may includeCr(CO)₆, Cr(C₆H₆)₂, Cr(C₅H₅)₂, CrF₂, CrCl₂, CrCl₃, the combinationthereof, or the like. Furthermore, the repair chamber 309 includes arepair tool 999 configured to emit beam BM (which can be electron beam(e-beam), laser, ion beam, or the like) over a predetermined area. Thebeam BM may disassociate bonding of the first gas 312, thus a solidmaterial can be formed in the predetermined area in localized manner.The beam BM can optionally be radiating in a fixed manner or a scanningmanner. For example, in the case of the first gas 312 is achromium-containing gas, by having the beam 392 irradiated over thefirst predetermined area DA1 (shown in FIG. 6), a chromium-containingfirst patch layer 12 can be locally formed in the first predeterminedarea DAL. In some embodiments, the first predetermined area DA1 isadjacent to a sidewall of the absorber layer 4, and the formed firstpatch layer 12 is in direct contact with the sidewall of the absorberlayer 4, as shown in FIG. 7B. In some embodiments, a thickness of thefirst patch layer 12 is comparable to a thickness of the absorber layer4. The first gas 312 is exhausted from the repair chamber 309 afterdeposition of the first patch layer 12.

Referring to FIG. 7C and FIG. 7D, FIG. 7C is a cross sectional view of aphotomask during intermediate repairing operations, FIG. 7D is a crosssectional view of a photomask during intermediate repairing operations,according to some embodiments of present disclosure. Subsequently, asecond gas 318 is introduced into the repair chamber 309 and applied onthe photomask 100. The second gas 318 is a precursor for forming asecond patch layer 18. The second gas 318 may be a silicon-containinggas which can serve as a precursor for forming a silicon derivativelayer. For example, the second gas 318 may be at least one of the SiH₄,SiCl₄, (CH₃O)₄Si, (C₂H₅O)₄Si, (CH₄SiO)₄, (CH₄SiO)₅, the combinationthereof, or the like. Furthermore, the repair tool 999 of the repairchamber 309 may emit beam BM over a predetermined area, thus the siliconderivative layer may form locally in such predetermined area.Optionally, the second gas 318 can be exhausted from the repair chamber309 after deposition of the second patch layer 18. In some embodiments,the formed second patch layer 18 entirely covers an exposed portion ofthe first patch layer 12. In some embodiments, a thickness of the secondpatch layer 18 over the sidewall of the first patch layer 12 is thinnerthan a thickness of the second patch layer 18 over the top surface ofthe first patch layer 12. In order to serve as a baseline of whether thesecond patch layer 18 can effectively prevent material loss thereof ormaterial loss of the first patch layer 12 during a subsequent cleaningoperation (as will be discussed in FIG. 11 to FIG. 14), a first criticaldimension CD1 of a selected mask feature adjacent to the second patchlayer 18 (or the first predetermined area DA1) is measured.

Referring to FIG. 7A′ and FIG. 7B′, FIG. 7A′ is a cross sectional viewof a photomask during intermediate repairing operations, FIG. 7B′ is across sectional view of a photomask during intermediate repairingoperations, according to some embodiments of present disclosure. Afteridentifying a first predetermined area DA1 having a defect as discussedin FIG. 6, a second gas 318 (similar to the counterpart discussed inFIG. 7C to FIG. 7D) is introduced into the repair chamber 309 andapplied on the photomask 100. By irradiating the beam BM over the firstpredetermined area DA1, the second patch layer 18 is locally depositedin the first predetermined area DA1. Optionally, the second gas 318 canbe exhausted from the repair chamber 309 after deposition of the secondpatch layer 18. In some embodiments, the first predetermined area DA1 isadjacent to a sidewall of the absorber layer 4, and the formed secondpatch layer 18 is in direct contact with the sidewall of the absorberlayer 4, as shown in FIG. 7B′. In some embodiments, a thickness of thesecond patch layer 18 is comparable to a thickness of the absorber layer4. In order to serve as a baseline of whether the second patch layer 18can effectively prevent material loss thereof during a subsequentcleaning operation (as will be discussed in FIG. 11 to FIG. 14), a firstcritical dimension CD1 of a selected mask feature adjacent to the secondpatch layer 18 (or the first predetermined area DA1) is measured. Itshould be noted that in the case of a material of the second patch layer18 can absorb light having other wavelength, such as 193 nm light, theaforesaid procedure in FIG. 7A′ can also be applied to the photomask 100x.

Referring to FIG. 8, FIG. 8 is a cross sectional view of a photomaskduring intermediate repairing operations, according to some embodimentsof present disclosure. A photomask 100 as discussed in FIG. 1A to FIG.2D, or alternatively photomask 100 y as discussed in FIG. 4A to FIG. 4Dis provided. In order to alleviate undesirable reflection or deflectionform the isolation region ISO, an inspection operation is performed inthe isolation region ISO of the photomask 100. The defect may include,but not limited to, particles PA that falls on the isolation region ISOof the photomask 100. Such particles PA may cause undesirablereflections and deteriorate the performance of lithography operation. Asshown in FIG. 8, a second predetermined area DA2 having a defect isidentified. It should be noted that the distribution of the particles PAmay be dispersed in some cases.

Referring to FIG. 8 and FIG. 9A to FIG. 9C, FIG. 9A to FIG. 9C are crosssectionals view of a photomask during intermediate repairing operations,according to some embodiments of present disclosure. Similar to thediscussion in FIG. 7A to FIG. 7B, a first gas 312 is introduced into therepair chamber 309 and applied on the photomask 100 (or photomask 100y). And by irradiating the beam BM over the second predetermined areaDA2, a first patch layer 12 is locally formed in the isolation regionISO to cover the particles PA in the second predetermined area DA2. Thefirst gas 312 is exhausted from the repair chamber 309, and the secondgas 318 is introduced into the repair chamber 309 and applied on thephotomask 100. By irradiating the beam BM over the second predeterminedarea DA2, a second patch layer 18 is locally formed over the first patchlayer 12. In some embodiments, the first patch layer 12 is entirelycovered and surrounded by the second patch layer 18. By forming thefirst patch layer 12 and/or the second patch layer 18, a portion of thelithography radiation (such as EUV) irradiated thereon can be absorbed.Accordingly, the reflection of light from in the isolation region ISOduring exposure operation can be alleviated.

In some embodiments, due to the constraint of the repair tool 999, asingle second predetermined area DA2 may be limited to a certain size(for example, 10 nm by 10 nm from top view). If a single secondpredetermined area DA2 cannot cover each of the identified particles,then it would be determined that the particles PA will be divided into aplurality of second predetermined areas DA2, and a plurality of secondpatch layer 18 may be formed, either connected or physically separated.In some embodiments, if the distribution of the particles PA is ratherdispersed, then the plurality of second patch layer 18 may be disposedat separated locations accordingly.

Referring to FIG. 9A′, FIG. 9A′ is a cross sectional view of a photomaskduring intermediate repairing operations, according to some embodimentsof present disclosure. Alternatively, subsequent to identifying a secondpredetermined area DA2 having a defect (as discussed in FIG. 8), thesecond gas 318 is introduced into the repair chamber 309 and applied onthe photomask 100. By irradiating the beam BM over the secondpredetermined area DA2, a second patch layer 18 is locally formed overthe particles PA. By forming the second patch layer 18, a portion of thelithography radiation (such as EUV) irradiated thereon can be absorbed.Accordingly, the reflection of light from the isolation region ISOduring exposure operation can be alleviated.

It should be noted that in the present disclosure, in some embodiments,repairing of the first predetermined area DA1 of the pattern region 6 isprior to repairing of the second predetermined area DA2 of the isolationregion ISO. In some other alternative embodiments, repairing of thefirst predetermined area DA1 of the pattern region 6 is subsequent torepairing of the second predetermined area DA2 of the isolation regionISO. In some other alternative embodiments, repairing of the secondpredetermined area DA2 of the isolation region ISO can be performedduring repairing of the first predetermined area DA1 of the patternregion 6.

In FIG. 10A to FIG. 10F, a portion of the fabrication operation(including repairing) of the photomask 100 x as discussed in FIG. 3A toFIG. 3B is provided. Referring to FIG. 10A, FIG. 10A is a crosssectional view of a photomask during intermediate manufacturingoperations, according to some embodiments of present disclosure. Anabsorber layer 4 is formed on a substrate 1 x, and a shielding layer 1 sis formed above the absorber layer 4 and patterned. Subsequently, theabsorber layer 4 is patterned by using the shielding layer 1 s as amask. A mask layer 4 m is further formed above the shielding layer 1 s.

Referring to FIG. 10B, FIG. 10B is a cross sectional view of a photomaskduring intermediate manufacturing operations, according to someembodiments of present disclosure. The shielding layer is exposed fromthe mask layer 4 m is removed by etching, thus a portion of the absorberlayer 4 is exposed from the shielding layer 1 s. Referring to FIG. 10C,FIG. 10C is a cross sectional view of a photomask during intermediatemanufacturing operations, according to some embodiments of presentdisclosure. The mask layer 4 m is thereby removed. In some embodiments,the mask layer 4 m is removed by stripping.

Referring to FIG. 10D, FIG. 10D is a cross sectional view of a photomaskduring intermediate manufacturing operations, according to someembodiments of present disclosure. Subsequently, an inspection operationis performed on the photomask 100 x to identify a predetermined area DAto be repaired. The defect in the predetermined area DA may include, butnot limited to, an absence of a desired photomask feature, an absence ofmaterial from a larger pattern feature, or any undesirable material lossof the photomask. For example, the pattern of the fabricated photomask100 x may be compared to a predetermined layout design, thereby identifythe defect of fabricated photomask 100 x that deviate from the originaldesirable design. For another example, the defect of the fabricatedphotomask 100 x may also be identified by experience or by algorithm.

Referring to FIG. 10E, FIG. 10E is a cross sectional view of a photomaskduring intermediate operations of manufacturing operations, according tosome embodiments of present disclosure. The first gas 312 is introducedinto the repair chamber 309 and applied on the photomask 100 x. Byirradiating the beam BM over the predetermined area DA, the first patchlayer 12 is locally deposited in the predetermined area DA. Optionally,the first gas 312 can be exhausted from the repair chamber 309 afterdeposition of the first patch layer 12. Referring to FIG. 10F, FIG. 10Fis a cross sectional view of a photomask during intermediate operationsof manufacturing operations, according to some embodiments of presentdisclosure. The second gas 318 is introduced into the repair chamber 309and applied on the photomask 100 x. By irradiating the beam BM over thepredetermined area DA, the second patch layer 18 is locally depositedover the first patch layer 12, and further covers a sidewall of thefirst patch layer 12. In some embodiments, the first patch layer 12 isentirely covered by the second patch layer 18. Optionally, the secondgas 318 can be exhausted from the repair chamber 309 after deposition ofthe first patch layer 18. In order to serve as a baseline of whether thesecond patch layer 18 can effectively prevent material loss thereof ormaterial loss of the first patch layer 12 during a subsequent cleaningoperation (as will be discussed in FIG. 11 to FIG. 14), a first criticaldimension CD1 of a selected mask feature adjacent to the second patchlayer 18 (or the first predetermined area DA1) is measured.

Referring to FIG. 11, FIG. 11 is a cross sectional view of a photomaskduring intermediate cleaning operations, according to some embodimentsof present disclosure. The repaired photomask 100 as any examplediscussed in FIG. 6 to FIG. 9A or FIG. 9A′ (or the repaired photomask100 x as discussed in FIG. 10A to FIG. 10F) is provided and positionedin a cleaning chamber 310. For the purpose of conciseness, hereinafterthe example of the photomask 100 is provided. It should be noted thatsimilar operation can also be applied to the repaired photomask 100 x.In a cleaning operation, a cleaning chemical 777 or a cleaning treatmentis applied on the photomask 100. The cleaning chemical 777 or thecleaning treatment includes, but not limited to, combination ofdeionized water and ozone (O₃), application of deionized water andirradiation of light (such as ultraviolet (UV)), combination of H₂O andhydrogen dioxide (H₂O₂), Sulfuric acid (H₂SO₄), SCl solution (solutionincluding NH₄OH, H₂O₂. H₂O), SPM solution (solution including H₂SO₄,H₂O₂, H₂O), wet chemical that includes acidic formulation, wet chemicalthat includes basic formulation, wet chemical that includes hydrogendioxide (H₂O₂), Ammonium hydroxide (NH₄OH), wet chemical that includesreactive chemical, or any other chemical suitable for cleaning aphotomask. During dispensing the cleaning chemical 777, the photomask100 is spun by a rotator, so the cleaning chemical can be spread outwith improved uniformity. The selected cleaning recipe may effectivelyremove some contaminations of the photomask 100. The cleaning operationillustrated in FIG. 11 is to introduce chemical force in the process.

In a comparative embodiment of a photomask only repairing with achromium-containing layer, a portion of the chromium-containing layermay be removed, and the pattern that can absorb incident light may bedistorted. The method for forming the photomask 100, photomask 100 y,and the photomask 100 x as provided in the present disclosure is able toalleviate the material loss of the patch layers deposited on thephotomask during the aforesaid cleaning cycles.

Referring to FIG. 12, FIG. 12 is a cross sectional view of a photomaskduring intermediate cleaning operations, according to some embodimentsof present disclosure. A photoresist 778 is coated on the photomask 100and cured. The photomask 100 is spun during applying the photoresist778. The cleaning operation illustrated in FIG. 12 is to introducespinning force in the process.

Referring to FIG. 13 and FIG. 14, FIG. 13 and FIG. 14 show crosssectional views of a photomask during intermediate cleaning operations,according to some embodiments of present disclosure. A cleaningoperation is performed by applying a cleaning chemical 777′ or bycleaning treatment. The cleaning chemical 777′ or the cleaning treatmentincludes, but not limited to, combination of deionized water and ozone(O₃), application of deionized water and irradiation of light (such asultraviolet (UV)), combination of H₂O and hydrogen dioxide (H₂O₂),Sulfuric acid (H₂SO₄), SCl solution (solution including NH₄OH, H₂O₂,H₂O), SPM solution (solution including H₂SO₄, H₂O₂, H₂O), wet chemicalthat includes acidic formulation, wet chemical that includes basicformulation, wet chemical that includes hydrogen dioxide (H₂O₂),Ammonium hydroxide (NH₄OH), wet chemical that includes reactivechemical, or any other chemical suitable for cleaning a photomask. Thephotomask 100 is spun during applying the cleaning chemical 777′.Optionally, a photoresist strip can optionally be performed to remove atleast a portion of the remaining photoresist 778. The cleaning operationillustrated in FIG. 13 is to introduce physical force by stripping off aphotoresist layer in the process.

Referring to FIG. 15A, FIG. 15A is a cross sectional view of a photomaskduring intermediate operations of repairing operations, according tosome embodiments of present disclosure. In order to serve as a baselineof whether the second patch layer 18 can effectively prevent materialloss, a second critical dimension CD2 of the selected mask feature,where the first critical dimension CD1 was previously measured, ismeasured and compared to the first critical dimension CD1. If adifference of the second critical dimension CD2 and the first criticaldimension CD1 (i.e. CD2−CD1) is less than a predetermined thresholdportion (such as 10%) of the first critical dimension CD1, the repairingof the photomask 100 can be deemed completed. Otherwise, the photomask100 may undergo the repairing operation and the cleaning operationagain. Alternatively, a thickness of the second patch layer 18, or thecombination of the first patch layer 12 and the second patch layer 18,can be used as a baseline. If such thickness decreases less than apredetermined value (such as 10 nm), the repairing of the photomask 100can be deemed completed. Alternatively, the pattern of the absorberlayer 4 and its adjacent patch layer (the first patch layer 12 and thesecond patch layer 18, or, only the second patch layer 18) can becompared to the predetermined layout design pattern.

Referring to FIG. 15B, FIG. 15B is a cross sectional view of a photomaskduring intermediate operations of repairing operations, according tosome embodiments of present disclosure. In some embodiments, the absorbrate (or the reflection rate) in the isolation region ISO can beinspected and used to determine whether the repairing of the photomask100 (or photomask 100 y) can be deemed completed, or repair should beperformed again.

Referring to FIG. 15C, FIG. 15C is a cross sectional view of a photomaskduring intermediate operations of repairing operations, according tosome embodiments of present disclosure. Similar to FIG. 15A, if adifference of the second critical dimension CD2 and the first criticaldimension CD1 (i.e. CD2−CD1) is less than a predetermined thresholdportion (such as 10%) of the first critical dimension CD1, the repairingof the photomask 100 x can be deemed completed. Alternatively, thepattern of the absorber layer 4 and its adjacent patch layer can becompared to the desirable layout design pattern. If the repairingoperation is deemed completed, a pellicle layer 1 y can be disposedabove the substrate 1 x of the photomask 100 x.

Referring to FIG. 16A, FIG. 16A shows a relationship between a thicknessof deposited patch layer in pattern region (left vertical axis) andnumber of cycles of cleaning operation performed, as well as arelationship between a change of critical dimension in pattern region(right vertical axis) and number of cycles of cleaning operationperformed, according to some embodiments of present disclosure. Curve P1and curve P1′ shows data points of a repaired photomask only depositedwith a first patch layer 12 in pattern region 6. Curve P2 and curve P2′shows data points of a repaired photomask deposited with the first patchlayer 12 and the second patch layer 18 covering the first patch layer 12in pattern region 6 (as shown in FIG. 2A or FIG. 15A). It can beobserved that by depositing the second patch layer 18 covering the firstpatch layer 12, after 4 cleaning cycles, critical dimension (CD %)enlargement is reduced from about 30% without the second patch layer 18to about 10% with the second patch layer 18, and the film height isgreater with the deposition of the second patch layer 18 than withoutthe second patch layer 18, evidencing that the material loss of therepaired photomask can be alleviated through the additional second patchlayer 18.

Referring to FIG. 16B, FIG. 16B shows a relationship between a thicknessof deposited patch layer in isolation region and number of cycles ofcleaning operation performed, according to some embodiments of presentdisclosure. Comparing to only depositing a first patch layer 12 in theisolation region ISO (curve P1″), further depositing a second patchlayer 18 covering the first patch layer 12 (curve P2″) alleviate thethickness loss of the repaired part in the isolation region ISO of thephotomask.

Referring to FIG. 16C, FIG. 16C shows a relationship between a thicknessof deposited patch layer and number of cycles of cleaning operationperformed, according to some embodiments of present disclosure.Comparing to only depositing a first patch layer 12 (line Q1),depositing only a second patch layer 18 (line Q2) or depositing a secondpatch layer 18 over the first patch layer 12 (line Q3) can bothalleviate thickness loss of the repaired part in the isolation regionISO of the photomask.

Referring to FIG. 17, FIG. 17 shows a flow chart representing a methodfor fabricating a semiconductor device, in accordance with someembodiments of the present disclosure. The method 9000 for fabricating asemiconductor device includes forming a photomask (operation 9001),forming a photoresist layer over a wafer (operation 9003), and exposingthe photoresist layer with actinic radiation through the photomask(operation 9009).

The photomask 100, 100 x, or 100 y provided in the present disclosurecan be positioned in an exposure chamber, and the photomask can be usedto pattern a photoresist layer coated on a wafer.

The present disclosure provides a photomask and a method for formingphotomask, specifically including repairing and cleaning the photomask.With regard to pattern region of a photomask, by depositing a secondpatch layer 18 (which may be a silicon derivative layer) over the firstpatch layer 12 (which may be a chromium-containing layer) adjacent tothe absorber layer 4 with defect, or by depositing a second patch layer18 (which may be a silicon derivative layer) adjacent to the absorberlayer 4 with defect, the material loss of the patch layer can bealleviated. With regard to the isolation region ISO of a photomask, bydepositing a second patch layer 18 (which may be a silicon derivativelayer) and the first patch layer 12 (which may be a chromium-containinglayer) over the detected particles in the isolation region, or bydepositing a second patch layer 18 (which may be a silicon derivativelayer) over the detected particles in the isolation region, thereflection issue from the isolation region can be alleviated. Therepairing methods provided by the present disclosure are incorporatedwith relatively strong cleaning treatment for effectively cleaningcontaminant.

Some embodiments of the present disclosure provide a photomask,including a substrate having a front side, an absorber layer over thefront side of the substrate, a first patch layer over the front side ofthe substrate and adjacent to a sidewall of the absorber layer, and asecond patch layer over the first patch layer.

Some embodiments of the present disclosure provide a photomask,including a substrate, an absorber layer over the substrate, a siliconderivative layer over the substrate, wherein a bottom surface of theabsorber is coplanar with a bottom layer of the silicon derivativelayer.

Some embodiments of the present disclosure provide a method forrepairing a photomask, including providing a photomask, wherein thephotomask comprises a substrate and an absorber layer over thesubstrate, applying a silicon-containing gas over the photomask, anddepositing a first silicon derivative layer adjacent to the absorberlayer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother operations and structures for carrying out the same purposesand/or achieving the same advantages of the embodiments introducedherein. Those skilled in the art should also realize that suchequivalent constructions do not depart from the spirit and scope of thepresent disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A photomask, comprising: a substrate; areflective multi-layer stack over the substrate; a capping layer overthe reflective multi-layer stack; an absorber layer over the cappinglayer; a first patch layer in direct contact with the absorber layer;and a second patch layer over a surface of the first patch layer.
 2. Thephotomask of claim 1, wherein a material of the first patch layercomprises chromium.
 3. The photomask of claim 1, wherein a material ofthe second patch layer comprises silicon oxide.
 4. The photomask ofclaim 1, wherein a material of the second patch layer comprises siliconcarbide.
 5. The photomask of claim 1, wherein the second patch layercomprises: a first portion above a top surface of the first patch layer;and a second portion lining a sidewall of the first patch layer.
 6. Thephotomask of claim 5, wherein a first thickness of the first portion ofthe second patch layer is greater than a second thickness of the secondportion of the second patch layer.
 7. The photomask of claim 6, whereinthe first thickness is in a range from 1 nm to 10 nm.
 8. The photomaskof claim 6, wherein the second thickness is in a range from 0.5 nm to 10nm.
 9. A photomask, comprising: a substrate, comprising an isolationregion and a pattern region different from the isolation region; anabsorber layer over the pattern region; and a first patch layer over theisolation region, wherein defect particle is at a position between thefirst patch layer and a top surface of the substrate over the isolationregion.
 10. The photomask of claim 9, further comprising a second patchlayer over the first patch layer.
 11. The photomask of claim 9, whereina material of the first patch layer comprises chromium.
 12. Thephotomask of claim 10, wherein a material of the second patch layercomprises silicon oxide.
 13. The photomask of claim 10, wherein amaterial of the second patch layer comprises silicon carbide.
 14. Thephotomask of claim 9, wherein a material of the first patch layercomprises a silicon-derivative material.
 15. A photomask, comprising: asubstrate, comprising a pattern region; an absorber layer over thepattern region of the substrate, comprising a first portion and a secondportion apart from the first portion; and a first patch layer over thesubstrate, wherein the first patch layer is in direct contact with thefirst portion of the absorber layer and apart from the second portion ofthe absorber layer.
 16. The photomask of claim 15, wherein a material ofthe first patch layer is silicon-derivative material.
 17. The photomaskof claim 15, wherein a material of the first patch layer is siliconoxide.
 18. The photomask of claim 15, wherein a material of the firstpatch layer is silicon carbide.
 19. The photomask of claim 15, wherein athickness of the first patch layer is in a range from 90% of a thicknessof the absorber layer to 110% of a thickness of the absorber layer. 20.The photomask of claim 15, further comprising a second patch layer overan isolation region over substrate and different from the patternregion, wherein a material of the second patch layer is identical to amaterial of the first patch layer.